i've run 33's on almost every gear ratio you can imagine that was ever in or made for xj's. 3.07, 3.55, 3.73, 4.10, 4.56, 4.88, the 4.88 were actually fine for me when going down the highway 70 at 2800 rpm was fine. but for the 35's go at least 4.88. it's better to overgear the axles and add an od in the driveline, then to have to re-do the axles again.